KR20140097363A - Aromatics isomerization using a dual-catalyst system - Google Patents

Abstract

The present invention relates to a process for isomerization of a non-equilibrium mixture of xylene and ethylbenzene containing a significant concentration of non-aromatics, comprising the steps of converting non-aromatics and obtaining improved yields of para-xylene from said mixture ≪ RTI ID = 0.0 > isomerization < / RTI >

Description

AROMATICS ISOMERIZATION USING A DUAL-CATALYST SYSTEM USING A DUAL-

STATEMENT OF PRIORITY

This application claims the benefit of priority to U.S. Provisional Application No. 61 / 559,226, filed November 14, 2011.

Technical field

The present invention relates to catalytic hydrocarbon conversion, and more particularly to the use of improved molecular sieve catalyst systems in aromatic isomerization.

Xylene, para-xylene, meta-xylene, and ortho-xylene are important intermediates that represent a wide variety of applications in chemical synthesis. Para-xylene produces synthetic fiber fibers upon oxidation and terephthalic acid used in the manufacture of resins. Meta-xylene is used in the manufacture of plasticizers, azo dyes, wood preservatives, and the like. Ortho-xylene is a feedstock for phthalic anhydride production.

Catalytic reforming or xylene isomers from other sources generally do not meet the demand proportion as a chemical reaction intermediate and further include ethylbenzene which is difficult to separate or convert. Para-xylene is the predominant chemical reaction intermediate, which is a particularly fast-growing order, but represents only 20-25% of the total C ₈ aromatic stream. The adjustment of the isomer ratio to the demand can be carried out by combining xylene-isomer recovery, for example, adsorption for para-xylene recovery, and isomerization to obtain an additional amount of the desired isomer. Isomerization converts a non-equilibrium mixture of xylene isomers with the desired xylene isomer into a mixture close to the equilibrium concentration.

Various catalysts and processes have been developed to effect xylene isomerization. In selecting the appropriate technique, it is desirable to carry out an isomerization process that is near equilibrium in order to maximize the para-xylene yield; Side reaction is accompanied by a larger cyclic C ₈ loss. The approach for the equilibrium used is an optimal trade-off between high cyclic C ₈ losses at high conversions (i. E., Very close approach to equilibrium) and high utility costs due to the high recycle rate of unconverted C ₈ aromatics. The catalysts are then evaluated based on an advantageous balance of activity, selectivity and stability.

Molecular sieve-containing catalysts have received attention for xylene isomerization reactions in recent decades. For example, U.S. Patent No. 3,856,872 teaches xylene isomerization and ethylbenzene conversion using ZSM-5, -12, or -21 zeolite-containing catalysts. U.S. Patent No. 4,899,011 teaches the isomerization of C ₈ aromatics using two zeolites associated with strong hydrogenated metals, respectively. U.S. Patent No. 6,142,941; U.S. Patent No. 7,297,830 B2; And U.S. Patent No. 7,525,008 B2 disclose zeolite catalysts useful for the isomerization of C ₈ aromatic compounds and are incorporated herein by reference. Although these references teach the individual elements of the present invention, no prior art document suggests that a combination of the above elements achieves important features of the catalyst system of the present invention.

Catalysts for the isomerization of C ₈ aromatics are usually classified by the way they process ethylbenzene associated with xylene isomers. Ethylbenzene is not easily isomerized to xylene but is generally converted in the isomerization unit because it is generally very costly to separate it from xylene by superfractionation or adsorption. A widely used approach is to dealkylate xylenes into a near-equilibrium mixture while dealkylating ethylbenzene to form predominantly benzene. An alternative approach is to react ethylbenzene through conversion to naphthene and re-conversion from naphthene in the presence of a solid acid catalyst with hydrogenation-dehydrogenation function to form a xylene mixture. The former approach often leads to higher ethylbenzene conversion and more efficient xylene isomerization, reducing the amount of recycle in the loop of isomerization / para-xylene recovery and reducing the cost of process processing.

SUMMARY OF THE INVENTION

The main object of the present invention is to provide a novel catalyst, and a process for isomerization of alkyl aromatic hydrocarbons. More particularly, the present invention relates to a catalyst system for the isomerization of C ₈ aromatic hydrocarbons containing significant concentrations of non-aromatic compounds to obtain high purity products.

Accordingly, a broad embodiment of the present invention is a process for the conversion of a hydrocarbon feed mixture comprising a major concentration of non-equilibrium C ₈ aromatics and a minor concentration of non-aromatics, the mixture comprising a tungsten component and Catalyst system comprising a first catalyst comprising one or both of at least one zeolite aluminosilicate and a second catalyst comprising from 0.01 to 0.2 mass-% of at least one platinum group metal component on an element basis, At a temperature of 550 DEG C, a pressure of 100 kPa to 5 MPa and a liquid hourly space velocity of 0.5 to 50 hr < ^-1 > for a dual-catalyst system, To obtain a converted product comprising a reduced concentration of ethylbenzene and a reduced concentration of a non-aromatic compound, To a method for converting a hydrocarbon feed mixture.

In one embodiment, the present invention relates to a process for the conversion of a hydrocarbon feed mixture comprising a high concentration of non-equilibrium C ₈ aromatics and a low concentration of non-aromatics, the mixture comprising 10 to 99 mass% of at least one zeolite aluminosilicate And a second catalyst comprising from 0.01 to 0.2 mass-% of at least one platinum group metal component on an element basis, and a second catalyst comprising a first catalyst comprising a first catalyst and a second catalyst comprising from 0.01 to 0.2 mass-% Pressure condition and a liquid space velocity per hour of from 0.5 to 50 hr < ^-1 > for a dual-catalyst system, whereby a higher ratio of at least one xylene isomer, reduced concentration of ethylbenzene and reduced To obtain a conversion product comprising a non-aromatics of concentration.

In an alternative embodiment, the present invention is a process for the conversion of a hydrocarbon feed mixture comprising a high concentration of non-equilibrium C ₈ aromatics and a low concentration of non-aromatics, the mixture comprising a first catalyst comprising a tungsten component, Catalyst system comprising a second catalyst comprising from 0.01 to 0.2 mass-% of at least one platinum group metal component and a second catalyst comprising a second catalyst comprising at least one of the following components: a temperature between 300 and 550 < 0 > C, a pressure between 100 kPa and 5 MPa, to about 50 hr ^-1 liquid hourly space velocity of the hydrocarbon-containing-conversion conditions by contacting the feed mixture in obtaining a conversion product comprising a non-aromatic compound of ethylbenzene and a reduced concentration of more reduced concentration of the mixture in the hydrocarbon feed .

These and other objects and embodiments will become apparent from the following detailed description of the invention.

The feedstock for aromatic isomerization is a compound of the formula C ₆ H _(6-n) R _n where n is an integer from 2 to 5 and R is CH ₃ , C ₂ H ₅ , C ₃ H ₇ , or C ₄ H ₉ ), including any combination thereof and all isomers thereof. Suitable alkylaromatic hydrocarbons include, for example, ortho-xylene, meta-xylene, para-xylene, ethylbenzene, ethyltoluene, tri-methylbenzene, di- -Isopropylbenzene, and mixtures thereof, but are not limited to the present invention.

Isomerization of a C ₈ aromatic mixture containing ethylbenzene and xylene is a particularly preferred application of the catalyst system of the present invention. Generally, such a mixture has an ethylbenzene content in the range of 1 to 50 mass-%, an ortho-xylene content in the range of 0 to 35 mass-%, a meta-xylene content in the range of 20 to 95 mass-%, a para- 30% by mass. The C ₈ aromatics mentioned above are preferably comprised of non-equilibrium mixtures, i.e. at least one C ₈ aromatic isomer exists at a concentration substantially different from the equilibrium concentration under isomerization conditions. Generally, non-equilibrium mixtures are prepared by removal of para-, ortho- and / or meta-xylene from new C ₈ aromatic mixtures obtained in an aromatic-compound production process.

Alkylaromatic hydrocarbons may be used as individual components obtained by selective fractionation and distillation of hydrocarbons which have been catalytically cracked or modified, as for example found in suitable fractions from refinery petroleum streams, or as specific boiling fractions, Can be used. The isomerizable aromatic hydrocarbons need not be concentrated; The process of the present invention isomerizes an alkylaromatic containing stream such as a catalyst modifier in the presence or absence of subsequent aromatic extraction to produce the specified xylenes isomers and in particular para-xylenes. The C8 aromatic feed to the process of the present invention may contain up to 30% by weight of non-aromatic hydrocarbons, i.e., naphthene and paraffin. The present invention is particularly useful for the processing of feedstocks containing non-aromatics at a concentration that can cause problems in other processes.

According to the process of the invention, an alkylaromatic hydrocarbon feed mixture is preferably contacted with two or more catalysts of the type described below in the alkylaromatic hydrocarbon isomerization zone, preferably in admixture with hydrogen. The contact may be carried out in a fixed-bed system, in a mobile bed system, in a fluidized bed system, in a slurry system or in an ebullated-bed system or in a batch-type operation using a catalytic system. In view of the risk of attrition loss of valuable catalysts and simpler work, it is desirable to use a fixed bed system. In this system, the hydrogen-rich gas and feed mixture are preheated to the desired reaction temperature by suitable heating means and then sent to an isomerization zone containing a fixed bed or layers of two or more catalysts. The conversion zone may be one or more separate reactors (with suitable means therebetween) so that the desired isomerization temperature is maintained at the inlet of each zone. The reactants may be in contact with the catalyst bed in a top-down, top-down, or radial flow manner, and the reactants may be in liquid phase, mixed liquid-vapor phase, or vapor phase upon contact with the catalyst.

The first and second catalysts may be included in separate reactors, arranged in series in the same reactor, physically mixed, or complexed as a single catalyst. Preferably, the catalysts are arranged in order so that the feed contacts the first catalyst to convert the non-aromatics to produce an intermediate stream for processing by the second catalyst to convert ethylbenzene and isomerize the aromatics, Lt; / RTI >

The position of the catalyst in the individual reactors enables independent control of operating conditions, in particular temperature and space velocity. However, by using a single reactor, cost savings are realized in piping, facility use and other accessory facilities. The physical mixing of the catalysts promotes the synergistic reaction of the catalyst, but the separation and recovery of the catalyst components may be more difficult. The catalyst system may be repeated in one or more additional steps, as the case may be, i.e. the reactants from the contact of the feed are processed in another order of the two catalysts.

Thus, in an alternate embodiment of the present invention, the reactor contains a physical mixture of the first and second catalysts. In this embodiment, the particles are mechanically mixed to provide a catalyst system of the present invention. The particles may be thoroughly mixed using known techniques such as mulling to intimately blend the physical mixture. Although the first and second particles may be of similar size and shape, the particles preferably have different sizes and / or densities for ease of separation for their regeneration or re-activation subsequent to their use in the hydrocarbon processing process.

In yet another alternative embodiment of the present invention, a physical mixture of the first and second catalysts is contained within the same catalyst particles. In this embodiment, the sieves may be ground or milled together or separately to form particles of suitable size, preferably less than 100 microns, and the particles are supported in a suitable matrix. Optimally, the matrix is selected from the inorganic oxides described above.

A non-equilibrium mixture of an alkyl aromatic feed mixture, preferably a C ₈ aromatics, is contacted with the catalyst system under suitable alkylaromatic-conversion conditions. Such conditions include temperatures in the range of 100 ° C to 600 ° C or higher, preferably in the range of 300 ° C to 550 ° C. The pressure is generally from 100 kPa to 5 MPa (absolute), preferably less than 3 MPa. A sufficient volume of both catalysts, including the catalyst system, is contained in the isomerization zone to provide a liquid hourly space velocity of 0.5 to 50 hr < ^-1 > for the hydrocarbon feed mixture, preferably 0.5 to 25 hr ^-1 , < / RTI > and the space velocity is in the range of 1 to 100 hr < ^-1 >. The hydrocarbon feed mixture is optimally mixed with hydrogen and reacted at a hydrogen / hydrocarbon molar ratio of from 0.5: 1 to 25: 1. Other inert diluents, such as nitrogen, argon and light hydrocarbons, may be present. When two or more catalysts are contained in separate layers, various operating conditions within the constraints can be used within each layer to achieve optimal overall results.

The particular scheme used to recover the isomerized product from the effluent of the reactor in the isomerization zone is not considered critical to the present invention and any effective recovery configuration known in the art may be used. Typically, the reactor effluent will be concentrated and the hydrogen and light hydrocarbon components are removed therefrom by flash separation. The concentrated liquid product is then fractionated to remove hard and / or heavy by-products and to obtain the isomerized product. In some cases, certain product species such as ortho-xylene can be recovered from the isomerized product by selective classification. The product obtained from the isomerization of the C ₈ aromatics is generally worked up, optionally recovering the para-xylene isomers by crystallization. Selective adsorption using crystalline aluminosilicates according to U.S. Patent No. 3,201,491 is preferred. Improvements and alternatives within the preferred adsorptive recovery process are disclosed in U.S. Patent Nos. 3,626,020; 3,696,107; 4,039,599; 4,184, 943; 4,381,419 and 4,402,832, which are incorporated herein by reference.

In a separation / isomerization process combination involving the processing of an ethylbenzene / xylene mixture, a new C ₈ aromatic feed is combined with an isomerized product comprising C ₈ aromatics and naphthenes from the isomerization reaction zone to form para-xylene separation Lt; / RTI > Xylene - - C ₈ para comprising a non-equilibrium mixture of aromatic compounds lacking stream is fed to the isomerization reaction zone, where the C ₈ aromatic isomers are isomerized to equilibrium levels to obtain the isomerized similar product. In this process configuration, the C ₈ aromatic isomers that are not recovered are preferably recycled until destruction until they are converted or lost to para-xylene due to side reactions. Preferably, the ortho-xylene separation by fractionation can also be carried out prior to para-xylene separation, on a new C ₈ aromatic feed or isomerized product, or a combination of the two.

The second catalyst may be a catalyst known in the art suitable for conversion of ethylbenzene and isomerization of xylenes. Preferred catalysts are spherical catalysts comprising a zeolite aluminosilicate, a platinum group metal component and an amorphous aluminum phosphate binder as described in U.S. Patent No. 6,143,941. The conversion of the non-aromatics contained in the feedstock by the first catalyst enables the use of such a catalyst.

The mass ratio of the first catalyst: the second catalyst is mainly dependent on the feedstock composition and the desired product distribution, with the first: second catalyst mass ratio being preferably 1:20 to 50: 1 and particularly preferably 1:10 to 20: 1 Do. The catalyst system of the present invention may include other catalysts that are sieve-based or amorphous.

The relative proportion of zeolite (if present in the first and second catalysts) may be in the range of from 10 to 99 mass-% and preferably from 20 to 90 mass-%.

The binder is a porous, adsorptive support having a surface area of 25 to 500 m < 2 > / g, a constant composition and relatively refractory to the conditions used in the hydrocarbon conversion process. The expression "homogeneous composition" means that the support is not layered, there is no concentration gradient inherent in the composition, and the composition is completely homogeneous. Thus, if the support is a mixture of two or more refractory materials, the relative amounts of these materials will be uniform and uniform throughout the entire support. (1) a refractory inorganic oxide such as alumina, titania, zirconia, chromia, zinc oxide, magnesia, tori, boria, silica-alumina, silica-magnesia, chromia, etc., which are traditionally used in hydrocarbon conversion catalysts, Alumina, alumina-boria, silica-zirconia, etc .; (2) ceramics, porcelain, bauxite; (3) Silica or silica gel, silicon carbide, clay and silicates, including those synthetically produced and naturally occurring, which may or may not be acid treated, such as, for example, ate pearlite clay, diatomaceous earth, Fuller's earth, kaolin, kieselguhr, etc .; (4) Crystalline zeolite aluminosilicates (made naturally or synthetically) such as FAU, MEL, MFI, MOR, MTW (according to the zeolite nomenclature in the IUPAC committee), (hydrogen form or exchanged form with metal cations ), (5) spinels example, MgAl ₂ O _4, FeAl ₂ O _4, ZnAl ₂ O _4, CaAl ₂ O _4, and the formula MO-Al or other similar compounds with ₂ O ₃ (where M is a metal Im having a valence 2 ); And (6) combinations of materials derived from at least one of these groups are included within the scope of the present invention.

A preferred refractory inorganic oxide for use in the present invention is alumina. Suitable alumina materials are crystalline alumina known as gamma-, eta-and theta-alumina, and gamma- or eta-alumina provides the best results. Preferably, the inorganic oxide is alumina, such as gamma-alumina. This gamma-alumina can be derived from boehmite or pseudoboehmite alumina (hereinafter collectively referred to as " boehmite alumina "). Boehmite alumina can be combined with a zeolite and extruded. During oxidation (or calcination), boehmite alumina can be converted to gamma-alumina. One preferred boehmite alumina used as starting material is VERSAL-251, available from UOP, LLC, Des Plaines, Illinois, USA. Another boehmite alumina can be sold under the trade name CATAPAL C by Sasol North America, Houston, Tex., USA. Generally, the production of alumina-bonded spheres involves the dropping of a mixture of molecular sieve, aluminum sol, and gelling agent into an oil bath maintained at elevated temperature. Examples of gelling agents that can be used in such processes include hexamethylenetetramine, urea, and mixtures thereof. The gellant may release ammonia at a high temperature that sets or converts the hydrosphere sphere to a hydrogel sphere. The spheres can then escape from the oil bath and are typically subjected to special aging in oil and ammonia solutions to further improve their physical properties. One exemplary oil dropping method is disclosed in U.S. Patent No. 2,620,314.

The alternative binder is a form of amorphous silica. The preferred amorphous silica is a synthetic, white, amorphous silica (silicon dioxide) powder that is classified as wet-processed, hydrated silica. This type of silica is produced by chemical reaction in an aqueous solution, from which it precipitates as ultrafine, spherical particles. The BET surface area of the silica is preferably in the range of 120 to 160 m < 2 > / g. A low content of sulfate salts is preferred, preferably less than 0.3 wt-%. It is particularly preferred that the amorphous silica binder is non-acidic, for example, the pH of the 5% aqueous suspension is neutral or basic (pH 7 or higher).

The preferred shape of the composite is a spherical shape continuously produced by the well known oil drop method. The preparation of alumina-bonded spheres generally entails the dropping of a mixture of molecular sieve, alumina sol, and gelling agent into an oil bath maintained at a high temperature. Alternatively, the gelation of silica hydrosol can be carried out using an oil-drop method. One method of gelling this mixture involves blending the gelling agent with the mixture followed by dispersing the resulting blended mixture in a heated oil bath or tower heated to elevated temperature to cause gelation as the spheroid particles are formed. The gelling agent that can be used in such a process is hexamethylenetetramine, urea or a mixture thereof. The gellant releases ammonia at a high temperature which sets or converts the hydrosoluble sphere to the hydrogel sphere. The sphere then continuously escapes from the oil bath and is typically aged in oil and ammonia solutions to further improve their physical properties.

An alternative shape for the catalyst composite is an extrudate. Known extrusion methods include mixing the non-zeolitic molecular sieve with a binder and a suitable peptizing agent before or after initially adding the metal components to form a homogeneous dough or thick paste with an appropriate moisture content Thereby allowing the formation of an extrudate having acceptable gums to withstand direct calcination. Extrudability is determined from the analysis of the moisture content of the dough, and a moisture content in the range of 30 to 50 wt-% is preferred. The dough is then extruded through a multi-hole die and the spaghetti-shaped extrudate is cut to form particles according to techniques known in the art. A wide variety of extrudate configurations are possible, including but not limited to cylinders, clover types, dumbbells, and symmetrical and asymmetric polylobates. It is also within the scope of the present invention that the extrudate can be further molded into any desired shape, e.g., spherical, by marumerization or any other means known in the art.

The resulting composite is then preferably washed and dried at a relatively low temperature of 50 to 200 DEG C and subjected to a calcination process at a temperature of 450 to 700 DEG C for 1 to 20 hours.

Each catalyst can be steaming to match the acid activity. Steaming can be carried out at any stage of the treatment but is generally carried out on a complex of zeolite and binder prior to the introduction of platinum group metals. Steaming conditions include a water concentration of from 5 to 100 volume-%, a pressure of from 100 kPa to 2 MPa, and a temperature of from 600 ° C to 1200 ° C; The steam treatment temperature is preferably 650 ° C to 1000 ° C, more preferably 750 ° C or more, and in some cases, 775 ° C or more. In some cases, temperatures of 800 ° C to 850 ° C or higher may be used. The steam treatment can be carried out for 1 hour or more, preferably 6 to 48 hours. Alternatively, or in addition to steaming, the composite may be washed with one or more of ammonium nitrate solution, mineral acid, and / or water. Washing can be carried out at any stage of the manufacturing and two or more stages of washing can be used.

Tungsten is a preferred component of the first catalyst. Tungstate ions are introduced into the catalyst composite, for example, by treatment with ammonium metatungstate, typically in a concentration of from 0.1 to 20 mass-% tungsten, preferably from 1 to 15 mass-% tungsten. Compounds such as metatungstic acid, sodium tungstate, ammonium tungstate, ammonium paratungstate, which can form calcined tungstate ions, can be used as an alternative source. Preferably, ammonium metatungstate is used to provide tungstate ions and form a solid strong acid catalyst. The tungstate content of the final catalyst is generally in the range of 0.5 to 30 mass-%, preferably 1 to 25 mass-%, based on the element. The tungsten complex is dried and preferably calcined at a temperature of 450 ° C to 1000 ° C, especially when tungstenation followed by introduction of a platinum group metal.

Platinum group metals, including one or more of platinum, palladium, rhodium, ruthenium, osmium, and iridium, are highly desirable components of each of the catalyst complexes of the present invention. A preferred platinum group metal is platinum. The relative platinum group metal content of each of the first and second catalysts is a feature of the present invention. The platinum group metal, if present, generally comprises from 0.01 to 0.5 mass%, preferably from 0.5 to 0.3 mass%, of the final first catalyst, calculated on an elemental basis; The second catalyst preferably comprises 0.01 to 0.5% by weight, preferably less than 0.2% by weight, especially 0.02 to 0.08% by weight, of platinum group metals on an element basis.

The platinum group metal component may be present in the final catalyst complex, for example, as a compound such as oxide, sulfide, halide, oxysulfide, or the like, or as elemental metal or with one or more other components of the catalyst complex. It is believed that the best results are obtained when substantially all the platinum group metal components are present in the reduced state. The platinum group metal component may be introduced into the catalyst complex in any suitable manner. One method of making the catalyst involves impregnating the calcined sieve / binder complex using a water soluble, degradable compound of a platinum group metal. Alternatively, the platinum group metal compound may be added at the time of complexing the sieve component and the binder. Complexes of the platinum group metals that may be used in the impregnation solution, extruded with the sieve and the binder or added by other known methods, include chloroplatinic acid, chloropalladic acid, ammonium chloroplatinate, bromoplatinic acid, platinum trichloride, (II), palladium chloride, palladium nitrate, palladium sulfate, diamine palladium (II) hydroxides such as platinum tetrachloride hydrate, platinum dichlorocarbonyl dichloride, tetramine platinum acid chloride, dinitrodiaminoplatinum , Tetraamine palladium (II) chloride, and the like. Preferably, the platinum group metal component is concentrated on the binder component of the catalyst by any method known in the art. One way to accomplish this desirable metal distribution is by compounding the metal components and binder before co-extruding the sieve and the binder.

The catalyst composites of the present invention may contain other metal components known to modify the effect of platinum group metal components within the scope of the present invention. Such metal modifiers may include rhenium, tin, germanium, lead, cobalt, nickel, indium, gallium, zinc, uranium, dysprosium, thallium, and mixtures thereof. Catalyst effective amounts of such metal modifiers can be introduced into the catalyst by any means known in the art to achieve a homogeneous or stratified distribution.

The catalyst of the present invention may contain a halogen component including fluorine, chlorine, bromine or iodine or a mixture thereof, preferably chlorine. Preferably, however, the catalyst does not contain additional halogens other than those associated with other catalyst components.

Each catalyst composite is dried at a temperature of 100 ° C. to 320 ° C. for 2 to 24 hours or more and is calcined in an air atmosphere at a temperature of typically 400 ° C. to 650 ° C. for 0.1 to 10 hours. If desired, any halogen component can be controlled by including a halogen or halogen containing compound in an air atmosphere.

The resulting calcined composite optimally ensures a uniform and finely divided dispersion of the specified metal components via a substantially water-free reduction step. Reduction may be optionally carried out in the process equipment of the present invention. Substantially pure and dry hydrogen (i.e., less than 20 vol. Ppm H ₂ O) is preferably used as a reducing agent at this stage. The reducing agent is contacted with the catalyst under conditions including a temperature of from 200 DEG C to 650 DEG C and from 0.5 to 10 hours effective to reduce substantially all of the Group VIII metal component to the metallic state. In some cases, the resulting reduced catalyst complex can also advantageously be pre-sulfided by methods known in the art to incorporate from 0.05 to 1.0 percent by weight of sulfur into the catalyst complex, calculated on an elemental basis.

Example

The following examples are presented solely to illustrate certain specific embodiments of the invention and should not be construed as limiting the scope of the invention as set forth in the claims. As will be appreciated by those skilled in the art, there are many other possible variations within the scope of the present invention.

A sample of the first catalyst for the conversion of the non-aromatics in the C ₈ -aromatic mixture was prepared and tested relatively in a pilot plant.

Example I

A catalyst comprising extruded particles of MTW zeolite complexed with alumina was prepared according to U.S. Patent No. 7,525,008 B2. The particles were impregnated with a solution of chloroplatinic acid, dried, oxidized, reduced and sulfided to give a catalyst containing 0.05 mass-% platinum. This catalyst was referred to as catalyst A.

Example II

Catalysts were prepared using the teachings of U.S. Patent No. 6,143,941. A reference oil-dropped spherical catalyst comprising a zeolite prepared according to Example I and an amorphous aluminum phosphate binder was reacted with ammonium sulphate (0.82 gram ammonium sulfate + 10 gram deionized water / gram support) at 60 <Exchange; After discarding, the ion exchange was repeated and the resulting spheres were washed 4 times with a 10 gram deionized water / gram support. The spheres were dried at 120 ° C for 1 hour and calcined at 350 ° C and 550 ° C in dry air for 2 hours. Spheres with a sulfur content of 0.7 mass-% were impregnated with tetraamine platinum chloride to achieve a platinum content of 0.04 mass-%, calcined in air with 3% steam at 525 [deg.] C for 2 hours, Lt; / RTI > The resulting catalyst was referred to as catalyst B.

Example III

Spherical alumina particles were prepared according to US 2,620,314 and metal-impregnated with ammonium metatungstate at pH 9-10 with the addition of NH ₄ OH to form a solid strong acid catalyst comprising 10 mass-% tungsten. The composite was dried and calcined in dry air at 350 < 0 > C and 550 < 0 > C for 3 hours. The complex was impregnated with an aqueous solution of chloroplatinic acid and hydrochloric acid at pH 9-10, dried at 350 ° C, ramped to 550 ° C at 50 ° C / hour, purged with nitrogen and reduced in hydrogen at 565 ° C for 1 hour Catalyst C "

Example IV

Particles comprising the active layer of MTW zeolite on a 1/16-inch gamma-alumina core were prepared according to U.S. Patent No. 7,297,830 to give a 150-micron layer of 10% MTW (40 Si / Al ₂ ratio). The particles were further impregnated with ammonium metatungstate to a pH of 10 by the addition of NH ₄ OH to form a solid strong acid catalyst containing 10 mass-% tungsten which was steamed and dried in dry air at 350 ° C and 550 ° C for 3 Calcined for a period of time. The complex was impregnated with an aqueous solution of chloroplatinic acid and hydrochloric acid at pH 9-10 according to Example III of US 7,297,830 to obtain a catalyst in which at least 90% of platinum was concentrated in the outer zeolite layer. The composite was dried and calcined and impregnated with an aqueous solution of chloroplatinic acid and hydrochloric acid according to Example III of U.S. Patent No. 7,297,830 to obtain a catalyst comprising at least 90% of platinum containing 0.28 mass-% platinum concentrated in the outer zeolite layer did. The particles were calcined and reduced to give Catalyst D.

Example V

Four Catalyst ADs were evaluated for the conversion of non-aromatics in C ₈ aromatics using a demonstration-plant flow reactor that processes unbalanced C ₈ aromatic feeds with the following composition (mass-%):

Catalysts tested: A and B C and D

Composition, mass -%:

Ethylbenzene 14.6 14.4

Meta-xylene 58.5 57.4

Ortho-xylene 24.4 24.3

Cumene 0.1 0.1

n-nonane 2.07 2.8

2-methyloctane-0.51

Trimethyl cyclohexane 0.27 0.49

Example VI

Four catalysts were tested under the following conditions:

12 hour weight space velocity

4 mole hydrogen / hydrocarbon ratio

385 ° C / 395 ° C / 405 ° C for 1-2 hours each

The conversion rate (%) is as follows: A B C D

n-nonane 96 80 41 86

2-methyloctane 16 12

Trimethyl cyclohexane 88 23 90 85

Ethylbenzene 30 58 8 11

Net byproducts, mass - 10% 4 6 7

Claims (9)

A process for the conversion of a hydrocarbon feed mixture comprising a major concentration of non-equilibrium C ₈ aromatics and a minor concentration of non-aromatics, the mixture comprising one or both of a tungsten component and at least one zeolite aluminosilicate And a second catalyst comprising 0.01 to 0.2% by mass of at least one platinum group metal component on an element basis, and a second catalyst comprising a first catalyst comprising a first catalyst comprising at least one of Catalyst system in a hydrocarbon-conversion condition comprising a liquid hourly space velocity of from 0.5 to 50 hr <" ¹ > relative to the pressure in the feed mixture and a reduced concentration of ethylbenzene and reduced concentration Of the non-aromatics of the hydrocarbon feed mixture. The process according to claim 1, wherein the concentration of the non-aromatics is 0.5 to 10 mass-% of the feed mixture. The method of claim 1, wherein the first catalyst comprises 0.01 to 0.3 mass-% platinum on an elemental basis. The process of claim 1, wherein the at least one zeolite aluminosilicate comprises MTW. The method of claim 1, wherein the first catalyst comprises a layered sphere. 2. The method of claim 1, wherein the first and second catalysts are sequentially laminated. The process of claim 1, wherein the catalyst system is a physical mixture of the first and second catalysts. The method of claim 1, wherein the first and second catalysts are contained on the same catalyst particle. 9. The process of claim 8, wherein the first catalyst comprises a layer on the surface of the second catalyst.